Current collector



Dec. 20, 1938. A. MEISSE V CURRENT COLLECTOR- F iled Aug. 10, 1937 I Inventor Laws .4 M51555.

A ttor nc y Patented Dec. 20, 1938 PATENT OFFICE CURRENT COLLECTOR Louis A. Meis se, Mansfield, Ohio, assignor to The Ohio Brass Company, Mansfield, Ohio, a corporation of New Jersey Application August 10,

10 Claims.

My invention relates to current collectors for use in connection with electrically operated vehicles and particularly to the sliding shoe or contact which is in direct engagement with the trolley wire.

The object of my invention is to provide a shoe which will have soft ends or noses with a hardened center.

My invention also resides in the method of producing a shoe in which the ends are relatively softand the center hard.

When I refer to shoe, I have in mind a one piece shoe or a shoe body which is provided with an insert.

I do not claim it is new to produce a shoe having soft ends or noses as shoes have been' made in the past of bronze with a hardened steel insert giving the full effect of a soft nose, see Larsson 2,044,886, issued June 23, 1936.

I claim, however, that I have produced a new and novel shoe and a new and novel method of producing a shoe with soft ends gradually be coming hard atthe center.

A shoe having soft ends with the intermediate portion which contacts with the trolley wire hardened is very desirable in that the same causes less damage to both the shoe and the overhead construction, and with decreased wear on the shoe and trolley wire if the central wire contacting portion of the shoe is hardened.

. The shoe in passing along the trolley wire is very apt to contact with the overhead'fittings such as ears, clamps, frogs, cross-overs, etc., and in doing so a shoe with a soft nose is less apt 35 to damage these devices and likewise less damage is done to the current collector without decreasing the life of the collector shoe.

In the construction disclosed in Larsson 2,044,886 in which the shoe body is of bronze and the entire insert of uniformly hardened steel, as the leading end of the bronze body wears away the end of the insert is more prominently exposed and will present a very hard cutting edge which in time will have its elfect upon the overhead fittings as well as the trolley wire.

In my invention the leading end of the shoe is relatively soft and this degree of softness gradually decreases toward the center of the shoe, thus eliminating any sharp cutting edge as de- 50 scribed above. The wear of the shoe gradually decreases from the leading end toward the center which, however, is hard and strongly resists wear.

In the drawing accompanying this specification:

1937, Serial N0. 158,330

Fig. l is a side View in partial section of a one piece shoe.

Fig. 2 is an end view of Fig. 1. v

Fig. 3'is a side View in'partial section of a shoe provided with a steel insert.

Fig. 4 isan end view of Fig. 3.

Fig. 5 is a side view in partial section of the insert shown in Fig. 3.

Fig. 6 is an end View of the insert.

Fig. 7 is an enlarged side view of the insert shown in Fig. 5 showing the hardness of the insert at various indentation points on the insert and the increase in hardness from the end toward the center.

Figs. 8 and 9 show an insert clamped between electrodes to be connected to a source of energy.

Fig. 10 shows a plurality of inserts manufactured as a unit and having their ends connected to electrodes adapted to be connected to a source of electric energy.

My invention does not reside entirely in the specific construction of the shoes but includes the relative hardness of the portions thereof and the method of producing the same.

In Fig. 1 the shoe comprises a body I of ferrous metal such as steel with means 2 to receive screws for holding the shoe in mounted position. The shoe is also provided with a groove 3 with up standing flanges 4. gated surface 5 for contacting with the trolley wire and has a curved surface 6 at the ends.

In Fig. 3 is shown a second form of shoe provided with a body portion I!) having an elongated slot H in which is mounted an insert l2. body H3 may be of bronze or soft steel or other ferrous metal while the insert is of steel subjected to the process herein disclosed.

Theinsert may be held in position by peening the edge l3 to lock the insert in position or it may be held by spot welding as is Well known to the trade.

The body I0 is provided with an elongated indent M on opposite sides of the body to receive clamping members to hold the shoe in mounted position.

The insert l2 has an elongated surface l5 which contacts with the trolley wire and a nose portion H5 at each end.

As the one piece shoe shown in Fig. l and the insert of the shoe shown in Fig. 5 are provided at each end with a soft nose 6 and I6 respectively, I. have indicated the soft portions by horizontal shade lines which are in addition to the oblique lines representing a section. It must be remem- The groove forms an elon- The bered that the change from the soft nose to the hard center is gradual. 7

Figs. 8 and 9 show the insert l2 as positioned between the electrodes 20 and 2|, preferably cooled as by means of water circulation entering at (a) and leaving at (b).

It will be noted that the electrodes are positioned at the ends of the insert and when current of low voltage and high amperage is passed from the positive electrode through the insert and through the negative electrode the center portion of the insert will be rapidly heated while the ends will remain comparatively cool and when the temperature at the center of the insert has passed the critical or transformation temperature the insert is subjected to a cooling medium such as water, air, or oil.

The central portion of the insert between the electrodes is very rapidly heated but the ends of the insert being clamped between cooled electrodes will be of a much lower temperature than the center, that is, the ends will not have reached the critical or transformation temperature by the time the center has reached or passed the critical or transformation temperature, therefore, the hardness of the insert will be a maximum at the center and a minimum at the ends after the insert has been rapidly cooled, in other words there will be a smooth gradient of decreasing hardness from the center of the insert toward the ends. This will be also true of the collector shown in Fig. 1 treated in the same manner as the insert l2 just described.

In Fig. 10 is shown another method of preparing the inserts in that the inserts are produced from a bar of steel of proper composition without severing the connection at their adjacent ends.

The bar of inserts is now heat treated by the Well known commercial method to produce the required hardness. This will depend upon the composition of the steel. 7

The ends of the bar of inserts are then connected to electrodes 22 and 23 which in turn are connected to a source of power. When current of low voltage and high amperage is passed through the bar the connecting portions 24 being of a much smaller cross-section than the inserts proper the portions 24 are rapidly heated and this heat will be transmitted to the end portions of the inserts and when a temperature sufiicient to relieve the temper at the ends has been reached the current is cut off and the bar removed from the electrodes and rapidly cooled.

The inserts are now separated from each other and will possess a smooth gradient of decreasing hardness from the center toward the ends thereof.

In Fig. 7 is shown a side view of an insert made of alloy steel SAE-34l5 having the following composition: 3.0% nickel; 0.6% chromium; 10%, to 20% carbon and 0.30% to 0.60% manganese. This insert was subjected to the process described with respect to the insert in Figs. 8 and 9 and then subjected to hardness tests. The small indentation circles indicate the position at which readings were taken and the figures at each circle show the exact Rockwell C readings and it will be noted that the readings increase in value from the end to the center thus indicating the gradual and smooth increase in hardness from the ends toward the center. The transverse lines may be said to indicate zone lines of hardness with gradual change of hardness between the zone lines. The figures at the end of the zone lines show the equivalent hardness on the Brinell scale.

Having fully described in the above specification'and the drawing my new and novel construction of current collector shoes and method of construction, I claim:-

1. A current collector shoe comprising a body of heat-treated steel having a portion intermediate the ends of the body with an elongated contact surface to engage a trolley wire and the said portion having rounded ends, the metal forming the said body having a gradual change in hardness from the maximum hardness adjacent the center of the said body to which the composition of the steel will permit to a maximum softness adjacent the ends thereof.

2. A current collector shoe comprising an elongated body of metal having a wire receiving groove, an elongated intermediate portion of heat-treated steel provided with an elongated straight surface to contact with said wire and downwardly curved end surfaces, the said intermediate portion being so tempered as to have a smooth gradient of decreasing hardness towards the ends of the collector, the maximum hardness being that to which the shoe is processed.

3. A current collector shoe comprising an elongated body of heat-treated steel having an elongated wearing portion with a surface to contact with a trolley wire, the said wearing portion having rounded ends of mild steel to reduce injury to the wire, the change in hardness of the wearing portion gradually decreasing from the center thereof toward the ends of the shoe.

4. An insert for a current collector comprising an elongated bar of heat-treated steel of nonuniform temper and having its maximum hardness adjacent the center portion of the insert and its maximum softness at the ends thereof to produce a contact surface having a temper gradient of decreasing hardness towards the ends of the insert whereby the insert has maximum resistance to wear at the center thereof.

5. A current collector comprising a body of non-ferrous metal and an insert of heat-treated ferrous metal having a contact surface to engage a trolley wire, the ends of the insert having a hardness not to exceed 225 on the Brinell scale while the hardness of the central portion of the insert exceeds that of the ends to permit a greater wear at the ends of the insert with a gradual decreasing wear towards the center portion of the insert.

6. A current collector comprising a body of metal and a separately formed heat-treated steel insert having an elongated contact surface to engage a trolley wire and also having exposed rounded ends, the temper of the insert ends not exceeding 225 as measured on the Brinell scale and gradually increasing to a value not less than 460 on same scale at the center.

'7. A current collector shoe comprising a body of metal and an insert of heat-treated steel having a contact surface to engage a trolley wire, the said insert having a maximum hardness at the longitudinal center thereof which the composition of the steel will permit and the said hardness decreasing towards the ends of the insert to prevent the ends injuring the trolley wire, the said heat treatment extending entirely through the body of the insert.

8. A current collector shoe comprising a body of heat-treated steel and having a groove with a contact surface for a portion thereof to engage a trolleywire, the hardness adjacent the longitudinal center of the shoe being substantially the maximum to which the steel may be processed and such hardness being uniform throughout the transverse plane through said center, the hardness of the shoe decreasing to the end thereof from that at the center and the hardness in any one transverse plane being substantially uniform.

9. A current collector shoe comprising a body of metal having a heat-treated insert of'steel, the maximum hardness which the treatment has produced being formed at the longitudinal center of the insert and the said hardness decreasing to the ends of the insert, to produce a long wearing contact surface at the center of the insert and which decreases towards the ends thereof.

10. In a current collector shoe, the combination with a holding member, of an insert to slidably engage the trolley wire, the insert being formed of steel and subjected to a heat treatment whereby the hard-ness resulting from the treatment will be a maximum adjacent the longitudinal center of the insert, the said hardness decreasing to the ends of the insert, producing an insert in which the life of the wearing surface will vary in like manner to that of the hardness.

LOUIS A. MEISSE. 

